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JSON to Yup Schema

Convert JSON into Yup validation schemas for forms and APIs. Objects, arrays, required, and optional rules are inferred from your sample data.

JSON input

Paste JSON, optionally name the root type, then generate.

Your Yup schema code will appear here.
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Schemas that match your data

Writing Yup schemas by hand for a big form means translating every field twice. This generator reads a sample JSON payload and writes the yup.object structure for you, marking consistently present fields as required and the rest as optional.

Drop it into Formik

Pair the generated schema with Formik's validationSchema prop and you get field level error messages with almost no extra code. The same schema can also validate the payload on submit before it hits your API.

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JSON to Yup Schema FAQs

What is Yup used for?
Yup is a schema builder for validating forms and API payloads, most famously paired with Formik in React. A schema describes the expected shape, then .validate() checks user input against it.
How does it decide required vs optional?
Fields present in every record become .required(), while fields missing from some array items or null in the sample stay optional, matching how the data actually varies.
Can the output validate nested forms?
Yes. Nested objects become nested yup.object() schemas, which is exactly the structure Formik expects for multi section forms like an address block inside a signup form.
Does it support arrays?
Yes. JSON arrays become yup.array().of(...), so a list of tags or order lines is validated item by item, not just as an opaque array.
Is Yup still maintained?
Yes. Yup remains one of the most used validation libraries in the React ecosystem and works with both JavaScript and TypeScript projects.
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